Re: receiver overload

Joe Puma
 

I heard that when you use an antenna tuner you actually raise the noise floor. 🤷🏻‍♂️I understand why but never heard it getting rid of noise. Maybe the tuner provided a better ground then what you had so yea maybe it made it seem like it reduced noise if your antenna system is inadequate.

Joe

On Apr 21, 2018, at 2:03 PM, Tim Gorman <tgorman2@...> wrote:

So what?

That site has nothing to do with how noise from static buildup sounds!

The original message said "I usually use a tuner beween the antenna and
the Bitexes - that works fine to tame the noise."

Again, the tuner can't tame the noise which is actually likely
atmospheric noise or electromagnetic interference from motors, lights,
etc. Those are all induced from external sources which the tuner can't
control.

BTW, the original message said he was using a form of dipole, not a
vertical.

Most antenna tuners, be they an L-network or a T-network, do not provide
a DC path to ground from both elements of an antenna. At least none
that I am familiar with. The only one that does is the Z-match. Most
Z-match tuners today are built for QRP only. Since my equipment has to
do multiple service, having a QRP only tuner isn't high on my to-do
list.

tim ab0wr




On Sat, 21 Apr 2018 12:14:49 -0500
"K9HZ" <@Doc_Bill> wrote:

Here: https://www.arraysolutions.com/antennas/static-bleed-inductor



Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ
PJ2/K9HZ

Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois

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Soufriere, St. Lucia W.I.
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-----Original Message-----
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Tim
Gorman Sent: Saturday, April 21, 2018 11:25 AM
To: BITX20@groups.io
Subject: Re: [BITX20] receiver overload

Noise from static buildup varies with the weather and wind. If you
think you have static buildup then all you have to do is disconnect
your antenna, use a jumper cable to short each element to ground, and
then reconnect the antenna. If your noise level drops significantly
then you had static buildup. If not, then you are hearing atmospheric
noise and/or phase noise in the receiver. The two can be
differentiated by just disconnecting the antenna to see what kind of
noise drop you see.

Noise from static buildup is typically not static. It does not sound
like the white noise, more like a buzzing or popping, and sometimes
even like a musical tone.

A tuner, even one that is isolated by a capacitor from the antenna,
typically won't "tune" static buildup noise. The noise is basically
from small discharges caused by charge equalization. Can you use your
tuner to to "tune-in" or "tune-out" the noise from the static
discharge of a lightning strike? Mine won't. The "noise" from the
lightning strike comes through no matter where the tuner is set.

If noise in the receiver goes up and down as you operate your tuner
to find the best match between your receiver and your antenna it's
because it is actually working. It is highly unlikely that the noise
you hear going up and down is from static buildup on the antenna.

tim ab0wr

On Fri, 20 Apr 2018 20:21:25 -0500
"K9HZ" <@Doc_Bill> wrote:

I guess that then assumes you have a very simple tuner (Cap-L leg)?
No impedance transformers, inductors to ground, etc.


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ
PJ2/K9HZ

Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois

Owner – Operator
Villa Grand Piton – J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com
Like us on Facebook!

Moderator – North American QRO Group at Groups.IO.

email: @Doc_Bill



-----Original Message-----
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Tim
Gorman Sent: Friday, April 20, 2018 8:18 PM
To: BITX20@groups.io
Subject: Re: [BITX20] receiver overload

I agree! But if the problem here is static buildup then a tuner
won't help any more than the coax connector on the rig!

tim ab0wr

On Fri, 20 Apr 2018 17:37:45 -0500
"K9HZ" <@Doc_Bill> wrote:

That is not where you want static charges dissipating! Chokes to
ground, resistors, at the antenna. All a better place for it (the
fire) to happen.


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ
PJ2/K9HZ

Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois

Owner – Operator
Villa Grand Piton – J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com
Like us on Facebook!

Moderator – North American QRO Group at Groups.IO.

email: @Doc_Bill



-----Original Message-----
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Tim
Gorman Sent: Friday, April 20, 2018 4:05 PM
To: BITX20@groups.io
Subject: Re: [BITX20] receiver overload

I'm sure it happens. But not consistently. You need wind and
something to create the charge like blowing dust. If the tuner is
dissipating the charge why doesn't the rig itself do it, at least
with an unbalanced feed?

tim ab0wr

On Fri, 20 Apr 2018 08:47:00 -0500
"K9HZ" <@Doc_Bill> wrote:

Unless the antenna is picking up a static charge and the
antenna tuner is acting like an impedance to ground draining
that charge off. Don't laugh, it happens.


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ
VP5/K9HZ PJ2/K9HZ

Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois

Owner – Operator
Villa Grand Piton – J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com
Like us on Facebook!

Moderator – North American QRO Group at Groups.IO.

email: @Doc_Bill



-----Original Message-----
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of
Tim Gorman Sent: Friday, April 20, 2018 8:42 AM
To: BITX20@groups.io
Subject: Re: [BITX20] receiver overload

Usually a tuner will increase noise, at least atmospheric
noise, as the tuner creates a match between the receiver and
the antenna. A matched antenna shouldn't "tame" the noise. If
that is actually happening then a closer look at the system
might be appropriate.

tim ab0wr



On Fri, 20 Apr 2018 11:39:39 +1000 "John Sharpe"
<johsharpe@...> wrote:

Hi all,

I just had a thought about new users of the uBitx and the
Bitx40.

I have both of these fine rigs but with my good antenna - a
ZS6BKW
<http://www.nc4fb.org/wordpress/zs6bkw-multi-band-antenna/> at
30 feet
- the receivers are swamped by noise and big signals on 40
metres.

When I tested just now a 59+ 10 signal on my IC-7300 was
unreadable on the Bitexes with the big antenna (which has a
low SWR at 40 metres) because of noise. With an antenna of
just 6 feet of wire in the shack the signal was readable (but
weak) on the Bitexes!

I usually use a tuner beween the antenna and the Bitexes -
that works fine to tame the noise. Also I have fitted an RF
control to the Bitx40 that helps quieten big signals.

But if you have lots of noise in the receiver and no tuner -
try a smaller antenna on receive (it will be no good for
transmitting). If that improves things maybe you need a tuner
or an RF control.

73s John V2VOL



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